Quote Originally Posted by abellringer View Post
The Webley MKIII S/T only ever had a tapered tap. The later Osprey had a parallel tap to reduce costs.
The MKIII tap was fitted as a slightly oversize part, the tapered hole reamed with special reamers, until the tap was almost in line with the bore, determined by a hardened steel probe gauge passed down the barrel; then the tap was coarse lapped with grinding paste, re checked and finally lapped in with fine paste all as per the valves in a car engine, this gave an air tight tap as per a gas tap. There was a range of tap sizes available because the breech block wasn't precision machined at its first stage, the barrel was in place before this initial reaming. If you have had to adjust the tap to be ''looser'' this sadly will cause an air leak and slight loss of power. I have some taps and factory reamers, but transport of the action might be a problem for you as it wouldn't be cheap. That would have to be your choice, but I would look at it for you if needed, not all guns are repairable if my taps are too small. Sadly you cant just buy one from J.K. or elsewhere and expect it to fit, the chances are like a lottery win. If your gun is later than No 44370 I can date it for you as I have the bench records from that number to end of production. E mail me at ray210645@yahoo.co.uk if needed and I'll do that for you.
I was factory trained for this and did a fair few over the years, before the production ended, as I was a service smith on several makes in the 70's and 80's.
abellringer
Very informative thanks